#include <iostream>
#include<string>
#include<vector>
using namespace std;
class Solution {
public:
    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
        vector<int>record1(1000, 0);
        vector<int>record2(1000, 0);
        for (int i = 0; i < nums1.size(); i++)
        {
            record1[nums1[i]]++;
        }
        for (int i = 0; i < nums2.size(); i++)
        {
            record2[nums2[i]]++;
        }
        vector<int>record3;
        for (int i = 0; i < 1000; i++)
        {
            if (record1[i] != 0 && record2[i] != 0) record3.push_back(i);
        }
        return record3;
    }
};
int main()
{
    vector<int> nums1 = { 4,9,5 };
    vector<int> nums2 = { 9,4,9,8,4 };
    Solution a;
    vector<int> nums3 = a.intersection(nums1, nums2);
    for(int i = 0 ;i<nums3.size();i++)
    cout <<nums3[i]<<' ';
    cout << endl;
  return 0;
}

class Solution {
public:
    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
        unordered_set<int> result;
        unordered_set<int> set1(nums1.begin() , nums1.end());
        for (int i = 0; i < nums2.size(); i++)
        {
            if (set1.find(nums2[i]) != set1.end()) 
            {
                result.insert(nums2[i]);
            }
        }
        return vector<int>(result.begin(), result.end());
    }
};

class Solution {
public:
    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
        unordered_set<int> result;
        unordered_set<int> set1(nums1.begin() , nums1.end());
        for (auto num : nums2)
        {
            if (set1.find(num) != set1.end()) 
            {
                result.insert(num);
            }
        }
        return vector<int>(result.begin(), result.end());
    }
};

class Solution {
public:
    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
        set<int> my_set;
        vector<int> result;
        for(int i=0 ;i<nums1.size();i++)
            my_set.insert(nums1[i]);
        for(int i=0 ;i<nums2.size();i++)
        {
            if(my_set.find(nums2[i]) != my_set.end())
            {
                 my_set.erase(nums2[i]);
                result.push_back(nums2[i]);
            }
        }
        return result;
    }
};